T m knowland



July 30, 1935. T. M. KNOWLAND 19,660

METHOD OF AND APPARATUS FOR VULCANIZING RUBBER ARTICLES Original Filed March 21, 19:53

Reissued July 30, 1935 Re,

UNITED STATES PATENT OFFICE.

19560 MET'IiOD OF ANI') APPARATUS R VUL- CANIZING RUBBER ARLTIC S Thomas M. Knowl'and, Belmoilt, Mass assignei' to Boston Woven Hose and Rubber Company,

Cambridge, Mass a corporation of Massachusetts Original No. 1,998,161, dated April 16, 1935, Serial No. 661387-2 March 21, 1933. Application for reissue June 11, 1935, Serial No. 26,008

is Claims. (01.1s--s) This invention relates to a'method of and appa- 15 a Side elevation, D y in o rains for vulcanizing elongated rubber articles,and ppa embodying the v o particularly rubber belting, whereby to p od Fig. 2 is an end elevation of the let-off reel, belting and the line havin little or no tendency with one form of braking device attached thereto. 5 to stretch. In one aspect thy invention consists in Referring w to h w n here n I h v a novel method of wl'cflinizihg elongated ru ber illustrated a machine for vulcanizing rubber beltarticles between a continuous band and a vul- Bind Simfla/T productst the 'c in genlirail canlzing drum while holding the article under a features of construction and mode of Operation constant and relatively high tension, built up may be that Shown in Patent 1,445,553

0 thEY'E-ili by the chem and band mm on the article issued February 13, 1923, and n w h H1 and after it leaves the supply roll and as it is being Ii! represent w rotatable drums e the p dr'awn r w rd a d m t drum, t at tension cries of which an endless flexible band or belt of being developed ih the article by surface friction metal is arranged to The band is enga ement therewith applied over substantial sinned by mechanism for moving the drums areas of the article whereby the tensioning and apart- Rvlls 22 maintain the flexible band in elongating thereof is effected Without deforming contact With the heated vulcanizmg drum the rt as by gripping or pinching it between The belting or other article to be vulcanized is squeeze 11 fed from the let-off reel Hi to the bite between the In another aspect my invention consists in a surface of the rotatable drum IE and the metal o 1 t n f Vulcanizing emngated rubber band M, as illustrated at 26-, and is vulcanized 20 articles llndel tensioh which is characterized by under the of the d filming the passing the article continuously from a supply reel Sage of the beltmg f the Perlphery of m t the vulcanizmg means and pmgressively drum, and, after leavmg the drum, the belting 1s stretching the article to greater tension in suewmmd on the suitable 3 25 cessive portions thereof during its passage from Heretofore, Vukanizmg opelianons have been the reel to the vulcanizing means, and holdlng the perform? P i feedmg f article to article under the relatively high tension thus proholdmg tlghtly m Contact Wlth F vulduced during the vulcanizing operation, whereby camzmg drum f' platen the article bemg thus t m produced is rendered unifmm in its fed and vulcanized substantially in its normal character throughout its length as hereinafter Condition and usually in an mtermittent mannerpointed out The resulting product has been a vulcanized Further w f the invention relate to a article lacking in uniformity particularly in that method and apparatus f r vulcanizmg ercngated different portions or sections thereof have dificrrubber articles wherein the article, as it is red entamoumnr 1 5 inherent from a supply reel to the vulcanizing drum, is 3 herein s provismn first stretched progressively to greater tension and for elemnatmg thls eblectmnable result thereafter placed under a predetermined tension, Pmdlwmg i substantially a or under a tension to stretch the article a prejm swash coemclem throughout its length, determined percentage of its length, prior to its provision im means 9 Placing the 40 a article under a relatwely h1gh tension as it is fed engagement with the drum, the article being 7 40 thereafter held in such condition during the vulm the Vulcamzmg drum and fur maintaining Such tension during the vulcanizing operation. camzmg P I The stretching or tensioning mechanism, pro-- The P y obleets of the mventlon are the vided in conjunction with the machine above pl'edumon of mpmved apparatus F nature described, builds up the tension in the belting or and for the Puma? and hereinafter F other article to apredetermlhed high degree durfined and the makmg avallable a and ing its travel from the let-on roll Hlto' the point Pmved method manufacture wherein Such zs where it enters between the drum m and the may be usefuny empmyedbelt in and maintains that requisite high tension 60 These Other features "U mventwn W upon the belting during vhleahization, while at be best understood and appreciated from the folthe ame time placing only a relatively small tenl w ns d s ip of a preferred emb d m nt sieh 0n the let-aft mechanism and thereby not therefore, Belem/6d I01 lilllpUSS 6f illustration interfering Withits lilial afiii l'lfirinfisl aberration. and shown if! tfi accompanying drawing iii 'fh said 'slfl'lthl'llg 0i ti isiiinlrlg meehahlsm I6, l1, i8, i9 and a tensioning sheave 20. The let-01f reel [5 comprises a shell 2|, upon which the belting or other vulcanizable material is wound, said shell having a square hole capable of receiving a square let-oil shaft 24. The let-01f shaft is mounted in the bearings 26-21 and is fitted at one end with a pulley sheave 28 which receives a tension strap 30. The tension strap 30 may be connected with any type of loading device desired, one form of which device being illustrated as comprising a lever 32 and weight 34. The belting to be vulcanized, after leaving the let-oil reel I 5, passes around the tensioning rolls at the point 26. The tensioning rolls are geared in train as illustrated and each is preferably finished with a roughened or fluted surface in order to reduce slippage of the belting thereon. The tension or break sheave 20 is geared at a reduced ratio to one of the tension rolls and restrains the rotation of the entire series of said rolls. The degree to which the tension sheave 2|) restrains the rotation of the tensioning rolls is dependent upon the Weight 59 which is attached to the tension sheave by the tension or brake strap 52 and this weight may be varied in accordance with the amount of tension it is desired to have in the belt during the vulcanizing operation. The rotation of the drum l furnishes to the belting the driving tension T| necessary to overcome the resistance of the tensioning rolls and to operate the let-off reel and this driving tension T-I is the predetermined tension under which it is desired to vulcanize the belting.

It is a well known fact that a belting passing around a pulley which offers resistance to rotation must be tensioned on the slack side and that this tension must bear a. certain minimum relationship to the driving tension, otherwise slippage will ensue. The brake 30 provides a sufiicient drag on the reel to keep the belting at T5 taut and eliminate any slack therein and the belting between the rolls is held taut due to the relation of and progressive increase of surface speeds in the succeeding rolls as hereinafter described. From known laws governing the relationship of the driving tension and slack tension around tensioning rolls, the number of tensioning rolls which are required progressively to reduce the driving tension T-J (vulcanizing tension) to a much lower tension at which it is desirable to have the let-off reel operate and which is indicated in the drawing as T5 may be determined. Under ordinary operating conditions attending the manufacture of commercial rubber belting, the use of three or four tensioning rolls will be suflicient to reduce the driving tension T--l (vulcanizing tension) to a tension value which is practicable for let-01f control. The number of tensioning rolls required will, however, depend upon the strength characteristics of the material which is being tensioned and the tension at which it is desirable to vulcanize the material.

The invention also contemplates a control of the relative surface speeds of the different tensioning rolls IS, IT, IS, IS and this may be accomplished by varying the number of teeth in the gears of the driving train or by varying the diameters of the different tensioning rolls. In the embodiment of the invention herein illustrated, the desired variations in the relative surface speeds of the different tensioning rolls is produced by varying the number of teeth in the gears. The relative surface speeds of the successive tensioning rolls Iii-l9 increase progressively and the tension in the belting is thereby built up progressively during the feed over such rolls, the increase in surface speed of the succeeding rolls serving to take up the stretch which is produced in the belting.

The required increase in the relative surface speeds necessary to cause and take up the stretch occurring in the belting in passing around the tensioning rolls is readily calculated from known laws and it is believed to be unnecessary for complete understanding of the present invention to discuss said laws herein. With a given material the stretch that take place in the material when subjected to a given tension is known or may be determined by test. It will be understood, however, that the increase in stretch rises as the stretching progresses and for this reason the rolls Iii-i9 will ordinarily be so related that the amount of stretch given to the belting at the succeeding stretching stages will progressively diminish as the stretching operation progresses. By taking up the stretch in the belting occurring between the different tensioning rolls as it passes around said rolls, slippage of the belt is minimized and possible slippage may be further reduced by providing as large an arcuate wrap as possible around each tensioning roll.

It will be understood that in passing from the roll Hi to the roll IS the belting is stretched a predetermined amount, depending upon the relation of the rolls, resulting in the belting being placed under a high tension. It is desirable that the belting shall be delivered to the vulcanizing drum at a predetermined tension or stretch and such tension or stretch is controlled through the action of the sheave 20 and the tension band 52 which serve to restrain the rotation of the entire train IE---!9 and therefore to impose a further tension on the belting at T-l.

The tension at T-l is the tension set up by the stretching operation as the belting passes over rolls iii-l9 plus the tension required to overcome the drag provided by the band 52 and its weight 50. It will therefore be seen that the tension T-i can be varied by varying the weight 50.

The present method and. apparatus produce a vulcanized article, and particularly a rubber belt ing, in which the amount of stretch remaining in the article or belt after vulcanization is substantially uniform because of the fact that the article is vulcanized under constant and uniform tension. In certain cases it may be desirable to vulcanize the article while in a condition stretched to a given percentage of its length. In such cases the gear train of the tension rolls, i6, I1, l8,

and I 9 may be geared directly to the rotating drum ID of the vulcanizing machine by a suitable gearing (not shown) and the speed of the drum relative to that of the train so regulated as to produce the desired percentage of stretch.

It will now be apparent that the belting or other article being vulcanized engages substantial arcuate areas of the rolls I 6-I9 and that, due to this contact, the frictional grip on the rolls is such as to provide the stretching tension required. It will furthermore be apparent that because of such frictional engagement with the article the article is not deformed during the tensioning and elongating thereof, as would be the case where it gripped between two elements, such as squeeze rollers along a line or narrow area of contact.

While a preferred embodiment of the invention has been herein illustrated and described, it will be understood that the invention may be embodied in other forms within the scope of the following claims.

Having thus described the invention, what is claimed is:-

1. In a continuous vulcanizing machine, in combination, vulcanizing means including a rotatable heated vulcanizing drum, a let-off mechanism, and means frictionally engaging substantial areas of the article to be vulcanized as it leaves the let-off mechanisn for progressively increasing the tension therein without deforming the article during its passage to the vulcanizing drum.

2. In a continuous vulcanizing machine, in combination vulcanizing means including a rotatable heated vulcanizing drum, a let-oif mechanism, and a plurality of rolls interposed between the let-off mechanism and the drum for respectively and frictionally engaging the article to be vulcanized over substantial arcuate areas of the rolls for progressively increasing the tension in the article during its passage to the vulcanizing drum.

3. In a continuous vulcanizing machine, in combination, vulcanizing means including a rotatable heated vulcanizing drum, a let-off mechanism, means interposed between the let-off mechanism and vulcanizing drum and cooperating with the article as it leaves the let-off mechanism for progressively increasing the tension in the article a substantial amount as it passes to the vulcanizing drum, said means comprising a series of tensioning rolls around substantial arcuate portions of which the article is irictionally engaged, and means for resisting the rotation of the tensioning rolls thereby to build up tension in the article.

4. In a machine for vulcanizing elongated rubber articles, in combination, a rotatable heated drum, means for exerting pressure on the article as it passes around the periphery of said drum, means for effecting vulcanization under heat and pressure, a let-off mechanism, and means interposed between the let-off mechanism and said drum and adapted frictionally to engage substantial surface areas of the article being fed to the drum to progressively increase the tension in the article from a relatively low to a relatively high amount without deforming the article.

5. In a continuous vulcanizing machine, in combination, vulcanizing means including a 1'0- tatable heated vulcanizing drum, a let-off mechanism for the article to be vulcanized, means cooperating with the article as it leaves the let-off mechanism for progressively increasing the tension therein during its passage to the vulcanizing drum, and means cooperating with the tensioning means for regulating the amount of tension established thereby.

6. A vulcanizing machine comprising in combination, a let-01f mechanism, a rotary vulcanizing drum, means cooperating with the drum to press the article to be vulcanized thereonto and draw it from the let-off mechanism as the drum is rotated, means between the let-off mechanism and drum for building up a substantial tension in the article as it is drawn toward and onto the drum, and variable means cooperating with and resisting movement of the second named means whereby to place a further and predetermined tension on that portion of the article between said second named means and the drum as the article is drawn toward and onto the drum.

'7. A continuous vulcanizing machine, comprising in combination, a let-off mechanism, a rotary vulcanizing drum, an endless band passing around and in contact with a substantial arcuate portion of the drum, the band and drum being advanced continuously to receive therebetween and draw from the let-01f mechanism rubber belting to be vulcanized, and means between the let-off mechanism and the drum for building up a substantial tension in and elongation of the belting as it is drawn toward and onto the drum.

8. In a continuous vulcanizing machine, in combination, vulcanizing means including a rotatable heated vulcanizing drum,a let-ofi mechanism, a plurality of tensioning rolls arranged in lateral alignment with and between the drum and let-oif mechanism in position to receive in contact with a substantial arcuate portion of each of such rolls the article to be vulcanized, and means so operatively connecting the rolls that the surface speeds thereof increase progressively from the let-off mechanism toward the drum.

9. The combination defined in claim 8, wherein the said rolls are of the same diameter and are operatively connected together to rotate at progressively greater speeds from the let-off mechanism toward the drum.

10. A method of continuously vulcanizing strip rubber belting or the like, consisting in continuously advancing the belting to vulcanizing position and progressively stretching the material to greater and greater tension and elongation at succeeding portions in its path of movement and during its passage to such position by surface frictional engagement therewith applied over substantial areas of the belting and holding the belting in and under such tension and elongated condition during vulcanization thereof.

ll. A method of continuously vulcanizing strip rubber belting or the like, consisting in continuously advancing the unvulcanized belting to vulcanizing position and progressively stretching the material to greater and greater tension and to a predetermined percentage of increase in its length at succeeding portions of its path of movement and during its passage to such position by surface frictional engagement therewith applied over substantial areas of the belting and holding the belting in and under such tension and elongation during vulcanization thereof.

12. A continuous method of vulcanizing fabric containing rubber belting or the like, consisting in continuously passing the belting to vulcanizing position and progressively stretching the belting to greater and greater tension and elongation in successive portions thereof during its passage to and as it approaches such position by surface frictional engagement therewith applied over substantial areas of the belting and holding the material in and under such tension and elongation during vulcanization thereof.

13. The method defined in claim 12 wherein the surface frictional engagement is applied only to opposite sides of the belting alternately at the ends of said portions.

THOMAS M. KNOWLAND. 

